公司mysql之前是一位离职员工在维护的。走了以后才让我维护，root密码不知道，吓死宝宝了。
[root ~]# mysql -u root
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password:NO)- 首先，停止mysql服务
[root ~]# service mysql stop
mysql stop/waiting- 启动mysql安全模式
[root ~]# mysqld_safe --skip-grant-tables &- 这时用root登录mysql就不需要密码了
[root ~]# mysql -u root
mysql>- 更改用户名，密码
mysql> use mysql;
Database changed
mysql> select * from user;
Empty set (0.00 sec)
mysql> truncate table user;
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to root@localhost identified by 'YourNewPassword' with grant option;
Query OK, 0 rows affected (0.01 sec)- 查看密码
mysql> select host, user from user;
+-----------+------+
| host | user |
+-----------+------+
| localhost | root |
+-----------+------+
1 row in set (0.00 sec)- 退出安全模式并杀掉进程，启动mysql服务
mysql> quit;
[root ~]# kill -KILL [PID of mysqld_safe]
[root ~]# kill -KILL [PID of mysqld]
[root ~]# service mysql start这个时候就可以登录了
[root ~]# mysql -u root -pYourNewPassword
mysql> 参考：
Access denied for user ‘root@localhost’ (using password:NO)